Bump rubocop from 1.7.0 to 1.8.1 (#15573)

* Bump rubocop from 1.7.0 to 1.8.1

Bumps [rubocop](https://github.com/rubocop-hq/rubocop) from 1.7.0 to 1.8.1.
- [Release notes](https://github.com/rubocop-hq/rubocop/releases)
- [Changelog](https://github.com/rubocop-hq/rubocop/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rubocop-hq/rubocop/compare/v1.7.0...v1.8.1

)

Signed-off-by: dependabot[bot] <support@github.com>

* Fix .codeclimate.yml

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Yamagishi Kazutoshi <ykzts@desire.sh>